Bridging plug



April 1967 o. J. MCCULLOUGH ETAL 3,314,479

BRIDGING PLUG 2 Sheets-Sheet 1 Filed Jan. 25, 1965 9/7 l o/he M #000 2 INVENTOR-S ATTORNEY April 1967 o. J. MCCULLOUGH ETAL 3,314,479

BRIDGING PLUG 2 Sheets-Sheet 2 Filed Jan. 25, 1965 INVENTORS United States Patent 3,314,479 BRIDGING PLUG Otis J. McCullough, McCullough Tool Co., P.O. Box 2575, Houston, Tex. 77001, Ira J. McCullough, McCullough Tool Co., 5820 S. Alameda, Los Angeles, Calif. 90058, and Vollie M. Hocut, Houston, Tex.; said Hocut assignor to said Otis J. McCullough and said Ira J. McCullough Filed Jan. 25, 1965, Ser. No. 427,796 Claims. (Cl. 16663) This invention relates to bridging plugs for wells and more particularly to a form of bridging plug'commonly termed a through-tubing plug.

In the operation and equipping of wells, such as oil and gas wells, it is frequently necessary to conduct operations such as cementing, gravel packing, and the like in a bore at some point above the bottom thereof. This condition normally requires the setting of a plug or other obstruction in the bore of the well pipe at the desired elevation above which the desired operations can be conducted. In many instances, such operations must be conducted in wells in which a string of casing is installed, as well as a smaller inner string of tubing, and it is necessary in order to perform the desired operations that the plug be set below the end of the tubing in the larger diameter casing. In order to avoid having to pull the string 'of tubing, which may be needed in the subsequent operations, as well as to avoid the expense and difiiculty of pulling the tubing, it is desirable to employ a form of plug which can be run into the Well through the smaller tubing below its lower end and thereafter expanded and set inside the larger casing.

- The so-called through tubing plugging devices heretofore employed have proven complicated in construction, ineflicient in their action, and particularly deficient in assuring anchoring in the larger pipe after expansion sufficiently strong to support the load of the material or equipment which is later to be deposited or landed thereon. As a result, such plugs tend to slip under the loads and render the operations for which they are intended wholly inelfective or unsatisfactory.

Accordingly, it is a primary object of this invention to provide an improved form of a through-tubing plugging device which avoids the defects and deficiencies of existing plugs of this general character.

An important object is the provision of a plug which can be run through smaller diameter tubing and expanded to seat in larger diameter pipe so as to form an effective bridge which will be strongly anchored to the larger pipe in which it is set.

A further object is the provision of an expansible through-tubing type of plug constructed of metal which is expansible by end-wise compression and which, when expanded, will define a plurality of gripping points or projections which will assure solid anchoring in a well casing.

Yet another object is the provision of a metallic plug which may be run through a smaller diameter tubing and expanded by end-wise compression into seating engagement in a larger pipe by explosive means.

A more specific object is the provision of a throughtubing type plug comprising an elongate tubular metallic body having an initial diameter such as to permit free movement through a smaller diameter pipe, and which isconstructed with a plurality of generally helical slots through the wall thereof such that when the ends of the body are compressed toward each other, the slotted body will expand to the required larger diameter to engage a larger diameter pipe in which it is to be set, and in which the resultant deformation of the portions of the body defined by the slots will form a plurality of teeth or like projections which will strongly anchor the body to the wall of the larger pipe into which it is expanded.

Still another object is the provision of a through-tubing plug of the character last described, in combination with an explosively actuated tool by means of which the opposite ends of the plug are driven toward each other to produce the desired radial expansion thereof.

Other and more specific objects and advantages of this invention will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawing which illustrates a useful embodiment in accordance with this invention.

In the drawing:

FIGS. 1A, 1B, and 10, together, constitute a view, partly in elevation and partly in section, of a bridging plug in accordance with this invention, together with an actuating or setting tool therefor shown inside a well pipe, such as a tubing;

FIG. 2 is a cross-sectional view taken along line 22 of FIG. 1C;

FIGS. 3A and 3B, together, illustrate the lower portion of the setting tool extended through the tubing and showing the parts in released position after the plug has been set in a larger diameter casing below the end of the tubing; and

FIG. 4 is a cross-sectional plan view taken along line 44 of FIG. 3B showing the upper end of the expanded bridging plug.

Referring first to FIGS. 1C and 2, which illustrates the bridging plug itself, it will be seen that the latter comprises a generally cylindrical body 10 having an axial bore 11. The lower end of body 10 is provided with an ex ternally threaded pin member 12 adapted to be received in a closure cap 13 to close off the lower end of bore 11. Body 10 is provided with a series of generally helical slots 14 which extend generally radially from the outer periphery entirely through the wall of the body and intersect bore 11.

The opposite ends of slots 14 are made to terminate short distances from the opposite ends of body 10 to provide non-slotted end portions 1717 at the opposite ends of the plug body. The arrangement of slots 14 thus provides a plurality of generally parallel helical segments 15 defined by the parallel edges 16 on the exterior faces thereof.

Body 10 is constructed of any suitable metal which may be steel, copper, brass, aluminum or various alloys thereof.' In general, aluminum will be preferred but any other metals may be found useful depending upon the conditions to be met in the field.

By providing the slotted construction as described, when the ends of body 10 are urged strongly toward each other, the body will be expanded radially to a considerably larger diameter, as illustrated for example in FIG.

3B. The end-wise compression and resulting expansion of the body produces a structure in its expanded form which has the general appearance illustrated in FIG. 3B and in which edges 16 of segments 15 tend to slide over one another so as to project slightly relative to one another to form projections indicated at 18 in FIG. 3B. These teeth or projections, under the expansive force applied to the plug, tend to bite into and grip the wall of casing C in which the device is set, and will thus effectively anchor the plug very strongly against slippage or displacement by any loads which will be subsequently supported thereon.

The expanded plug thus assumes a basket-like configu ration providing, as noted, a multiplicity of sharp edges spaced along substantially the full length of the expanded plug to assure strong gripping action on the surrounding pipe wall. The non-slotted ends 1717 assure against tearing apart of the plug segments so as to proa vide a substantially firm end surface to receive the material or apparatus to be supported thereon.

'It will be understood that the plug may be made in any suitable length and its diameter will be such as to allow it to be lowered freely through the bore of a tubing'and when subjected to the appropriate end-wise compression, will be expanded to the desired diameter necessary to assure a tightly anchored bridge or plug in the larger diameter pipe in which it is to be set. For example, to provide a plug to be run through 2 tubing and set in /2" casing, plug body may be made 1%" in external diameter and 16" in length, which, when appropriately expanded, will seat tightly in the 5 /2" casing and will occupy a compressed length of about 5 /2" or 6".

The plug body is mounted on an elongate cylindrical mandrel 45 which extends slidably through bore 11 into the bore of pin member 12 to which the lower end of the mandrel is releasably secured by a frangible shear pin 52 which extends transversely through registering openings in pin member 12 and mandrel 45. The latter is made somewhat longer than body 10 to project above the upper end of the latter. The projecting upper end portion is provided with a section of external threads 45a to provide means for attachment of the mandrel to a setting tool to be described subsequently. The upper end portion of the mandrel is provided with a short axial bore 46 which communicates with lateral ports 48, 48 opening to the exterior of the mandrel below the section of threads 45a for purposes to be described hereinafter.

While various types of tools, mechanically, pneumatically or hydraulically actuated, may be employed to compress and expand the plug after it has been run through the tubing into the larger casing into which it is to be set, a setting tool of the explosively-actuated type is preferred in accordance with the present invention.

In the embodiment illustrated in the drawing, the setting tool comprises a tubular body having an axial bore defining a firing chamber 21, the upper end of which is enlarged and internally threaded to form a socket 22 for connection of a conventional firing head 23 having an axial bore 24. The firing head is, in turn, connected in the usual manner to a rope socket 25 which is carried on a cable 26 which leads to the surface, and carries threaded therethrough an electrical conductor 27 which leads into bore '24 of the firing head. Conductor 27 is connected to an electrode 28 which is, in turn, operatively connected to an electrically fired explosive cap 29 mounted in a firing barrel 30 screwed into the lower end of firing head 23. The lower end of body 20 is connected by means of a threaded sub 31 to a tubular cylinder 32, the lower end of which is closed by a bushing forming a cylinder head 33 which is screwed into the lower end of cylinder 32 and has an outer end portion 34- adapted to bear against upper end portion 17 of the bridging plug. For purposes of this description, portion 34 may be termed an anvil by reason of the function which it is to perform in the setting of the plug, as will appear hereinafter.

Slidably disposed in bore 35 of cylinder 32 is a piston 36 carrying an annular seal packing 37 for sealing slidably with the wall of bore 35. Piston 36 has an axial bore 36a to receive the lower end of a hollow piston rod 38 having an axial bore 38a. Piston rod 38 is fixedly secured in the upper end of bore 36a'and extends up wardly through bore 35 and thence through a bore 39 in sub 31 into firing chamber 21 of body 20.

Longitudinally spaced seal packings 49, 41 are disposed in the wall of bore 39 'in slidable sealing engagement about piston rod 38. Relief ports 42 are provided through the wall of cylinder 32 near its upper end below the seal packings 40, 41 to communicate bore 35 with the exterior of the cylinder. The lower end of piston bore 36a is internally threaded to receive the threaded uper end of mandrel 45 co-axially with rod 38 so that bore 4'6 will register with bore 3811, thereby positioning lateral ports -48 to open into an expansible pressure chamber 49 defined inside bore 35 between the upper end of cylinder head 33 and the lower end of piston 36. An annular seal packing 51 is disposed in cylinder head 33 about mandrel 45.

When mandrel 45 has been connected as described to piston 36, anvil 34 will be positioned to bear against the upper end of body 10 of the bridging plug and, with the lower end of the mandrel releasably secured to the lower end of body 10 by means ofshear pin 52, it will be seen that as a strong upward force is applied to the mandrel while maintaining anvil 34 relatively stationary, a strong end-wise compressive force will be applied to the opposite ends of the plug body 10 causing the latter, by reason of the helically slotted construction of the body, to be laterally or radially expanded to an extent limited by the confines of casing C in which the plug is run.

In order to apply the required compressive force, a charge of a conventional propellant explosive 55 is disposed in the upper end of firing chamber '21 spaced at short distance belowv cap 29. An orifice plug 56 is mounted in the upper end of the firing chamber between cap 29 and the propellant charge 55 and has an axial orifice passageway 57 therethrough in which is installeda check valve 58 to permit only downward flow of gases, such as are generated by setting off of propellant charge 55. Orifice passageway 57 is designed to transmit a jet of flame from cap 29 to the propellant charge in order to ignite the latter. The propellant charge is seated on a hollow spacer sleeve 60 having an axial bore 62 and provided with numerous perforations 61 through the wall thereof. Spacer sleeve 60 extends downwardly through the firing chamber and is dimensioned to slidably receive piston rod 38 in bore 62 of the sleeve. Bore 38a of the piston rod will be in open communication with bore 62 of the spacer sleeve for transmitting the high pressure gases resulting from explosion of propellant charge 55 through ports 48 into pressure chamber 49.

Operation of the device is as follows: Bridging plug 10 secured to mandrel 45 and mounted in the setting tool string, as shown in FIGS. 1A, 1B and- 1C, will be run into a well on cable 26 through a tubing string T until the bridging plug has passed below the lower end of tubing string T into casing C to the point at which the plug is to be set. Thereupon, electrical current will be sent through conductor 27 to fire cap 29. The jet of flame from the latter will pass through orifice passageway 57 and will ignite propellant charge 55. The resulting explosively created gases will then travel through spacer sleeve 60 into and through bore 38a of the piston rod from which the high pressure explosive gases will flow through ports 48 into pressure chamber 49. a

The explosive forces entering chamber 49 will act upwardly on piston 36 and mandrel 45 and downwardly against cylinder head 33. The upward force thus applied to mandrel 45 will be exerted against the lower end of body 10 tending to compress the body in a longitudinal or end-wise direction against anvil 34, which will remain relatively stationary, thereupon expanding .thebridging plug into tight engagement with the wall of casing C. Almost instantaneously following compression of the bridging plug, under the high velocity forces involved, shear pin 52 will shear and allow mandrel 45 to move upwardly out of bore 11 of the bridging plug, piston 36 traveling upwardly in cylinder 33 to the upper position illustrated particularly in FIG. 3A. Any fluid or gases trapped in bore 39 between piston 36 and sub 31 willbe vented through ports 42, thus preventing any restriction on the upward movement of the piston andthe connected mandrel. Release of the mandrel by severing shear pin '52, will permit the setting tool to be withdrawn from the tive to each other in such manner as to cause slight overlapping of adjacent edges 16 of the plug segments causing them to project slightly from the exterior of the plug body to thereby define the teeth or projections 18, which, under the strong expansive forces, serve to securely anchor the plug at numerous points to the wall of easing C, under sufiicient force to effectively support the loads which will thereafter be applied to the plug.

The number of segments into which the plug body may be divided may vary widely, depending largely upon the the extent of expansion and degree of tightness and com pactness sought for the expanded plug. In the example mentioned previously, the plug, constructed of aluminum, was divided into eight helical segments each about onehalf inch wide, separated by slots about one-eighth inch wide.

It will be understood that numerous changes and modifications may be made in the details of the illustrative embodiment, both of the bridging plug itself and of the plug and setting tool combination herein described, within the scope of the appended claims but without departing from the spirit of the invention.

What we claim and desire to secure by Letters Patent 13:

1. A through-tubing bridging plug for use in wells, comprising, a cylindrical metallic body having an initial diameter to pass through a relatively small diameter pipe and having an axial through-bore, a plurality of generally helical slots cut radially entirely through the wall of the body to intersect said bore and define a plurality of generally parallel helical segments, said slots terminating at points spaced from the opposite ends of the body to define non-slotted annular end-portions on the body, said body being radially expansible to a substantially larger diameter by application of end-wise compressive force to the opposite ends thereof, whereby to effectively plug a relatively large diameter pipe.

2. A through-tubing bridging plug according to claim 1 wherein the adjacent sides of said helical segments define relatively sharp outer marginal edges projectible from the periphery of the body by the expansion thereof for anchoring engagement with the wall of the larger diameter pipe.

3. A through-tubing bridging plug for use in wells, comprising, a cylindrical metallic body having an initial diameter to pass through a relatively small diameter pipe and having an axial through-bore, a plurality of generally helical slots cut radially entirely through the wall of the body to intersect said bore and defining a plurality of generally parallel helical segments, said slots terminating at points spaced from the opposite ends of the body to define non-slotted annular end-portions on the body, said body being radially expansible to a substantially larger diameter by application of end-wise compressive force to the opposite ends thereof, whereby to effectively plug a relatively large diameter pipe, and means operably connected to opposite ends of said body for applying said endwise compressive force thereto.

4. A through-tubing bridging plug according to claim 3 wherein the adjacent sides of said segments define relatively sharp outer marginal edges projectible from the periphery of the body by the expansion thereof for anchoring engagement with the wall of the larger diameter pipe.

5. A through-tubing bridging plug according to claim 3 wherein said last-mentioned means comprises relatively movable force-applying members engaging opposite ends of said body, and force-supply means operably connected to both said members to forcibly urge said members toward each other.

6. A through-tubing bridging plug according to claim 5 wherein said force-supply means is an explosivelyactuated means.

7. A through-tubing bridging plug for use in wells, comprising, a cylindrical metallic body having an initial diameter to pass through a relatively small diameter pipe and having an axial through-bore, a plurality of generally helical slots cut radially entirely through the wall of the body to intersect said bore and defining a plurality of generally parallel helical segments, said slots terminating at points spaced from the opposite ends of the body to define non-slotted annular end-portions on the body, said body being radially expansible to a substantially larger diameter by application of end-wise compressive force to the opposite ends thereof, whereby to effectively plug a relatively larger diameter pipe, a mandrel extending into said bore, releasably securing said mandrel to the lower end portion of said body, annular abutment means engaging the upper end portion of said body and slidably receiving said mandrel, and force-supply means operably connected to said mandrel and said abutment means to forcibly urge them toward each other.

8. A through-tubing bridging plug according to claim 7 wherein said force-supply means is an explosively-actuated means.

9. A through-tubing bridging plug according to claim 7 wherein said force-supplying means comprises, a hollow cylinder, a cylinder head closing one end of said cylinder and defining said abutment means, a firing chamber connected to the opposite end of said cylinder, a piston slidable in said cylinder and defining with said cylinder head an expansible pressure chamber, means connecting the upper end of said mandrel to said piston, a piston rod connected to said piston, a passageway through said piston rod and piston communicating said firing chamber with said pressure chamber, a charge of explosive in said pressure chamber, and means for igniting said explosive.

10. A through-tubing bridging plug for use in wells, comprising, a cylindrical metallic body having an initial diameter to pass through a relatively small diameter pipe and having an axial through-bore, a plurality of generally helical slots cut radially entirely through the wall of the body to intersect said bore and define a plurality of generally parallel helical segments, said slots terminating at points spaced from the opposite ends of the body to define non-slotted annular end-portions on the body, said body being radially expansible to a substantially larger diameter by application of end-wise compressive force to the opposite ends thereof whereby to effectively plug a relatively large diameter pipe, a mandrel extending into said here, frangible means releasably connecting said mandrel to the lower end portion of said body, and means carried by the upper end portion of the mandrel for connecting the same to means adapted to produce said end- Wise compressive force.

References Cited by the Examiner UNITED STATES PATENTS Re. 16,670 7/1927 Bell 166196 X 1,493,717 5/1924 Wilson 166192 X 2,244,076 6/1941 Moe 166192 2,830,540 4/1958 Vincent 166-496 X 3,026,939 3/1962 Sweetman 16663 X 3,282,346 11/1966 Claycomb 166182 JACOB L. NACKENOFF, Primary Examiner. D. H. BROWN, Assistant Examiner. 

1. A THROUGH-TUBING BRIDGING PLUG FOR USE IN WELLS, COMPRISING, A CYLINDRICAL METALLIC BODY HAVING AN INITIAL DIAMETER TO PASS THROUGH A RELATIVELY SMALL DIAMETER PIPE AND HAVING AN AXIAL THROUGH-BORE, A PLURALITY OF GENERALLY HELICAL SLOTS CUT RADIALLY ENTIRELY THROUGH THE WALL OF THE BODY TO INTERSECT SAID BORE AND DEFINE A PLURALITY OF GENERALLY PARALLEL HELICAL SEGMENTS, SAID SLOTS TERMINATING AT POINTS SPACED FROM THE OPPOSITE ENDS OF THE BODY TO DEFINE NON-SLOTTED ANNULAR END-PORTIONS ON THE BODY, SAID BODY BEING RADIALLY EXPANSIBLE TO A SUBSTANTIALLY LARGER DIAMETER BY APPLICATION OF END-WISE COMPRESSIVE FORCE TO THE OPPOSITE ENDS THEREOF, WHEREBY TO EFFECTIVELY PLUG A RELATIVELY LARGE DIAMETER PIPE. 